2VCO Problems

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izze
 
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2VCO Problems

Post by izze »

Hello
I installed my 2 VCO from x0xsh0p today, but it seems to sound a little too dirty.. i tuned it, but it still sounds very unclear. Is this normal ?
Also the Tuning of the First VCO isnt as accurate as it was before (using the as X0x tune vst plugin).

There is a Resistor (RX) that is supposed to be 100K it says that it can be changed to other values if needed ? I am not sure about that?

Thanks
Patrick

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antto
 
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Re: 2VCO Problems

Post by antto »

so, you tuned your VCO with the VST
then installed the mod
and after that your VCO is no longer in tune?

that's possible i guess, simply retune it
what exactly do you mean with "dirty"

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altitude
 
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Re: 2VCO Problems

Post by altitude »

It should be very clear. on mine I have to check my level pots to see which is which. Describe a little better what it sounds like

Luap
 
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Re: 2VCO Problems

Post by Luap »

I've installed one of these kits too. And it did cause me to have to retune the original osc. But once that was done, there were no other tuning or noise issues that I noticed.
It can be a little tricky to tune both oscs correctly, but its important to do it as best you can, or it will sound ugly.

izze
 
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Re: 2VCO Problems

Post by izze »

In comparison to the first osc it sounds "distorted" "unclear".. it also seems not to respond to the filters settings properly. I already tuned the pots so they match as good as possible to the first osc. I got almost all Pots completely turned up, so i can only tune the 2VCO down, tuning it all the way up makes it to match the pitch of osc 1.

I dont really know why this isnt working.

Regarding the as x0x tune: When i first tuned the osc 1 it had exactly 1.000 - 2.000 in both settings. After installing the 2 VCO it was like 0.957 - 1.937 and the best after tuning it for 10 minutes is 0.997 - 2.011 bouncing between 1.005 - 2.000 variing all the time. so it is not static anymore. I dont really understand how this can be...

Also which resistor did you install on the RX section. In the manual it says 100K, thats what i did

izze
 
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Re: 2VCO Problems

Post by izze »

Hey guys.. i uploaded a sound sample.. please tell me what could be wrong with it.
At first it was just the first osc... then i added 2VCO Saw.. fiddled around abit.. then 2VCO Square.... and at the end i adjustet the tune of the 2VCO down... and up..

Would be nice if anyone could tell me what is wrong.

http://k004.kiwi6.com/hotlink/eu736mz8dz/x0xb0x2vco.mp3


Edit: I removed OSC1 by cutting the trace to R62. When there is no OSC present i seem to hear the Sequencer ?! Is this normal its like a ticking noise in the lower frequency range. Also the Filter seems to chirp by himself without OSC.

After that i tuned OSC2 with as x0x tune, if i turn off OSC1 it seems that OSC2 sounds the same by itself.. so that problem solved.


Please help me out
Last edited by izze on Tue Apr 03, 2012 4:59 pm, edited 1 time in total.

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substyler
 
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Re: 2VCO Problems

Post by substyler »

hi Izze,

could you show me a sharp picture of your 2VCO build?
it seems that the two thermistors are wrong soldered or something...
what about the trimmer pots? there is a 5k and a 50k, are they properly soldered?

cheers,
SubStyler

izze
 
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Re: 2VCO Problems

Post by izze »

hey substyler..
Thanks for your time.. i edited the above post. OSC 1 and OSC 2 now sound almost the same by themselves.

But i still got the problem that i can hear the sequencer, even with no OSC turned on.. i can also hear it when a osc is turned on.

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substyler
 
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Re: 2VCO Problems

Post by substyler »

yes, this ticking noise is still there. also that chirping noise is normal, the VCF is self-oscillating.
some x0xen have it less, some x0xen have it more.
there are some workarounds to kill that gate noise. dig the forum.

cheers,
SubStyler

izze
 
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Re: 2VCO Problems

Post by izze »

OK i found some mods to help making the gate noise a little less loud.

But there is no real fix for it..
There are alot of different suggestions around.. one with a 10m resistor and a 50K trimmer pot, others with a 100NF or 150NF cap, and so on. i guess i will try all the options.

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altitude
 
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Re: 2VCO Problems

Post by altitude »

Sound sample sounds OK to me, I dont hear anything obviously wrong with it. With the 2nd VCO, I really think you should consider adding a level control to it, it really makes a difference

izze
 
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Re: 2VCO Problems

Post by izze »

Hey altitude
What kind of level control do you mean ?

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altitude
 
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Re: 2VCO Problems

Post by altitude »

One to control the mix level of the 2nd VCO. I wrote up a thread about how I did mine.

http://forums.adafruit.com/viewtopic.php?f=13&t=20301

guest
 
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Re: 2VCO Problems

Post by guest »

this was a recent attack fix
http://adafruit.com/forums/viewtopic.php?f=12&t=25779

i havent tried it myself
but i liked the concept behind it

izze
 
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Re: 2VCO Problems

Post by izze »

Ok i will try that.. whatever that middle pin to Q1 to "whatever pin on the BA6110" means :o ?!
I guess he means the pin where Q1 would normally go to ? or am i wrong ?
Can i also use one of the pins from the BA662 section ? If so i will try that one tonight, would save me an order for parts for the other mods.

Thanks

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